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AW: Dirty bombs- Cs-137 movement into soil question
-----Ursprüngliche Nachricht-----
Von: owner-radsafe@list.vanderbilt.edu
[mailto:owner-radsafe@list.vanderbilt.edu]Im Auftrag von BERNARD L COHEN
Gesendet: Montag, 03. März 2003 16:05
An: Stewart Farber
Cc: Jim Hardeman; Radsafe
Betreff: Re: Dirty bombs- Cs-137 movement into soil question
>
> For fresh fallout, sitting on the soil surface one uses a specified factor
of
> flux to areal concentration. As time goes on Cs "moves" into the soil and
the
> flux for any average areal concentration would go down. However, Cs does
not
> reach a depth where it is difficult to measure by field gamma
spectroscopy,
> although on a sandy surface [with little if any organic content] with lots
of
> rain over many years, Cs might penetrate to a much greater depth.
--Are the depths involved sufficient to give appreciable
shielding for health protection purposes? How effective would it be to
plow the surface under to some depth? In ion exchange columns, there are
many ways to desorb the adsorbed materials; would that be effective for
washing the Cs deeper into the soil? Of course, removing the soil surface
would not be a very expensive approach if it nothing else worked.
------------------------------
It is not clear to me, whether you refer to a nuclear accident with very
widespread contamination or to a "dirty bomb". But since a dirty bomb would
not be exploded on arable land, I rather assume that you refer to a nuclear
accident.
After the Chernobyl accident there were some ideas in Austria to deep-plough
the soil to move the Cs-137 to deeper layers. It was not done, because this
deep-ploughing would destroy the soil, so that hardly anything would grow on
it any more. Being a chemist I do not know of any chelating agents which
would selectively chelate Cs-137 and wash it into deeper layers. Of course
there is the possibility to desorb Cs-137 with agents like lactic acid,
EDTA, acetic acid or similar agents - but then you can forget about growing
any crops on that soil. After the Chernobyl accident some "green" groups
claimed, that the top soil should be removed from Austrian soil and that the
removed soil should be stored at our nuclear research center. I do not
remember the exact numbers, but you can easily calculate, what amount of
soil in cubic-kilometers would have piled up to remove about 30 cm deep soil
in an area of a few tens of thousands of square kilometers of arable land in
Austria.
Sorry to say, but your proposed solution of handling such a contamination is
far away from anything reasonable and acceptable. We have to work nowadays
together with all kind of other sciences - agriculture, chemists,
ecologists - in order to solve our problems.
Best regards,
Franz
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